Method for Representing Vehicle Surroundings

ABSTRACT

The invention relates to a method for representing vehicle surroundings for a vehicle ( 1 ) having a sensor system for detecting the environment, wherein a boundary of a traffic lane on which the vehicle is currently being driven is represented by position points ( 4, 7, 8, 11 ) that have a predefined set of attributes.

Nearly all currently available driver assistance systems based on data provided by environment monitoring sensors use an object abstract environment model. Typically an object list of surrounding objects is provided. Such an approach does not cover areas where no objects are present and which define a potential maneuvering space. In the field of research, approaches are known which use sensors providing space occupancy information about a defined area surrounding the vehicle and entering said information on a space occupancy map. Such a representation permits indirect estimations of the available maneuvering space. A disadvantage of this method, however, is that the space occupancy map (occupancy grid) contains large amounts of data which are currently too large to be usable in a commercial application, since the bandwidths provided by typical CAN connections for the communication between control devices are not sufficient for real-time transmission.

It is the object of the present invention to provide a method for representing a maneuvering space in a vehicle environment using a reduced amount of data.

The object is accomplished according to the independent claims.

A key component of the present invention is the representation of a succession of boundaries of a traffic lane currently being driven (1) by position points (4, 7, 8, 11) that have a predefined set of attributes. The succession of boundaries results e.g. from the positions of traffic lane markings, building site fences, roadside structures, guardrails, (parking) vehicles at the roadside, etc.

Preferably, the distance, in particular a longitudinal distance, and the number of position points (4, 7, 8, 11) can be predefined adaptively depending on at least one of the following parameters:

i) speed of the ego-vehicle itself; for example, a large longitudinal distance between the position points will be selected for representing traffic lane markings in particular in motorway scenarios; a correspondingly smaller distance between the position points is preferentially selected for modeling the maneuvering space boundaries during parking maneuvers. Preferably, a large distance is chosen when driving at high speed and, correspondingly, a small distance when driving at low speed.

ii) complexity of the scenario; e.g. a small distance between the position points is required in a driving situation in the city with many surrounding objects and traffic signs

iii) curve of the traffic lane; a small distance between the position points is required on winding road sections

iv) width of the traffic lane; in particular, if the traffic lane becomes wider, a larger distance between the position points can be selected.

In a preferred embodiment of the present invention, an attribute of the position points (4, 7, 8) indicates a lateral width. The lateral width is a measurement of an area that is usable as maneuvering space and located on the other side of the position point, i.e. outside the traffic lane delimited by the position points (4, 7, 8, 11). The lateral width is e.g. large if another traffic lane where the vehicle can be freely driven is present on the other side of the traversable traffic lane markings. The lateral width will be set e.g. to a small value or to zero if a non-traversable roadside structure, e.g. a slope, directly starts on the other side of traversable traffic lane markings. Preferably, the lateral width directly indicates the width of a maneuvering space opposite a position point.

The lateral width of position points (8) representing non-traversable traffic lane boundaries such as guardrails or building site fences preferably equals zero.

In a further embodiment of the present invention, the lateral width of position points (7) representing traversable traffic lane markings is larger than zero.

In a preferred embodiment of the invention, the lateral width of position points representing traversable traffic lane markings equals zero if a lane change of the ego-vehicle to the adjacent lane, said adjacent lane also being delimited by s said position points, would at this position lead to a risk of collisions with oncoming or overtaking vehicles (9).

In an advantageous embodiment of the invention there is a further attribute of the position points (11). The further attribute indicates a measure of a narrowing of the area inside the traffic lane delimited by the position points that is usable as maneuvering space. In other words, this attribute indicates whether the whole area delimited by position points can be used as maneuvering space or whether there are obstacles (12) which must be bypassed.

In particular, the further attribute is assigned a predefined standard value if no obstacle is present in the traffic lane. In a further advantageous embodiment of the invention, the further attribute assumes a value deviating from the predefined standard value in the case of position points delimiting a road section where an obstacle (11) is present.

In an advantageous embodiment, the further attribute indicates which area and/or how much space is actually available as maneuvering space.

A further claim is directed to a method for a driver assistance system which determines for a vehicle (1) a future trajectory based on data provided by a sensor system for detecting the environment. For this purpose, surrounding objects and their positions are detected using the sensor data and the vehicle surroundings of the ego-vehicle are represented via position points using the detected objects by means of a method as described above. This representation of the surroundings is transmitted via a vehicle bus to a control device. The control device is designed in such a way that a future trajectory of the ego-vehicle can be determined.

An additional claim is directed to a driver assistance system with a sensor system for detecting the environment and a data evaluation unit operating by a method as described above. For this purpose, the data evaluation unit is connected via a vehicle bus system to a control device which controls a driver assistance function.

In the following, the invention will be described in greater detail using embodiments and drawings.

The starting point is the traffic lane 1 currently being driven on by the ego-vehicle 2 as illustrated in FIG. 1. Said traffic lane is defined as the open space ahead up to the respective lateral boundary. These boundaries may represent, for example, traffic lane markings, structural boundaries, in particular building site traffic barriers, and/or static objects which laterally restrict the traffic lane currently being driven. The course and the form of the traffic lane 1 are preferably represented by both a left-side and a right-side list of position points. The number of position points and the longitudinal distance between them can be adapted to the current requirements of the respective situation according to criteria such as the speed of the vehicle itself or the complexity of the scenario. Each position point can have a certain predefined set of attributes as illustrated in FIG. 2. A central attribute in this context is the lateral width of the area on the other side of the position point. Such a representation covers e.g. also the “non-traversable” property by providing a value of zero for the lateral width, as e.g. illustrated in FIG. 3. There the vehicle is driving into a building site area 6. In the area where the traffic lane 1 adjoins the building site 6, the position points 8 are assigned the attribute lateral width equal zero. Outside the building site area the position points 7 are assigned the attribute lateral width larger than zero.

The width of the traffic lane 1 that is usable as maneuvering space can also be restricted by moving objects, for example other vehicles, on the other side of the boundary line. In a preferred embodiment of the present invention, this restriction is described by the attribute of lateral width. Even if the line is physically traversable at the moment of observation, a traffic lane boundary is marked as “non-traversable”, in particular using position points 8, if a crossing of the boundary is unsafe due to an oncoming traffic situation or due to a vehicle approaching from behind, as illustrated in FIG. 4.

FIG. 6 a shows an exemplary scene where a lane is narrowed at one point by a stationary vehicle 12 at the roadside. The boundaries 13 on both sides of the lane are traversable. The identical scene is illustrated in FIG. 6 b with position points 7, 8 delimiting the traffic lane 1; the outline of the stationary vehicle 12 was taken into account. The position points 8 delimiting the stationary vehicle are assigned the attribute of lateral width equal zero because the traffic lane boundary is not traversable at this point. The other position points 7 which are not delimiting the stationary vehicle are assigned the attribute of lateral width larger than zero because the traffic lane boundary is traversable at this point.

Stationary objects occupying the traffic lane currently being driven can be modeled by using a further attribute representing the remaining maneuvering space between the two boundary lines. This attribute assumes a predefined standard value if no obstacle is present on the traffic lane. In a preferred embodiment of the invention, the further attribute otherwise assumes the remaining free space as a physical distance value. This scenario is illustrated exemplarily in FIG. 5. Shown there is an obstacle 10 (in this case a stationary motorbike) on the traffic lane 1 of the ego-vehicle 2. Position points 11 with attributes indicate the narrowing at the position of the obstacle.

Advantages of the invention presented here are the complete description of the open space ahead within the current traffic lane and the representation of the lateral traversability as a basis for determining the trajectory for leaving the traffic lane currently being driven, if necessary. The particular advantage of representing the situation using a list of boundary points is the fact that arbitrary traffic lane courses can be described, and the effort involved is also smaller than required by an analytical representation. It is possible to represent arbitrary courses of the current traffic lane; the abstract point information greatly reduces the required amounts of data compared to a dense open space representation, permitting the use of production-ready means of communication such as CAN. In particular, the representation of the boundaries of the current path is sensor-independent, meaning that whenever new features become detectable by new sensors, it is no problem to account for said features in the representation; one example of this would be curbs.

REFERENCE SYMBOL LIST

-   1 traffic lane currently being driven -   2 ego-vehicle -   3 left traffic lane boundary -   4 right traffic lane boundary -   5 position point with attributes -   6 building site -   7 traversable position point with a lateral width larger than zero -   8 non-traversable position point with a lateral width equal zero -   9 other vehicle -   10 obstacle in the traffic lane, e.g. a stationary object     (motorbike) -   11 position point with the attribute narrowing larger than zero -   12 vehicle at the roadside -   13 traversable boundaries on both sides 

1. A method for representing vehicle surroundings for a subject vehicle traveling on a road and having a sensor system for detecting the environment, wherein a boundary of a traffic lane on the road is represented by position points that have a predefined set of attributes, and the attributes include a width attribute which indicates a lateral width that is a width measurement of an area usable as a maneuvering space outside the traffic lane on an opposite side of the boundary of the traffic lane represented by the position points.
 2. The method according to claim 1, characterized in that a longitudinal distance and a number of position points are predefined adaptively depending on at least one of the following parameters: a) a speed of the subject vehicle, b) a complexity of a scenario detected by the sensor system, c) a curve of the traffic lane, d) a detected narrowing or widening of the open space traffic lane.
 3. (canceled)
 4. The method according to claim 1, characterized in that the lateral width indicated by the width attribute of ones of the position points representing non-traversable traffic lane boundaries equals zero.
 5. The method according to claim 1, characterized in that the lateral width indicated by the width attribute of ones of the position points representing traversable traffic lane boundaries is greater than zero.
 6. The method according to claim 1, characterized in that the lateral width indicated by the width attribute of ones of the position points representing traversable traffic lane markings equals zero if a lane change of the subject vehicle into an adjacent lane, which is also delimited by the position points, would lead to a risk of collisions with oncoming or overtaking vehicles.
 7. The method according to claim 1, characterized in that the attributes of the position points include a further attribute that indicates a measure of a narrowing of an area inside the traffic lane that is usable as an in-lane maneuvering space.
 8. The method according to claim 7, characterized in that the further attribute is assigned a predefined value if no obstacle is present in the traffic lane.
 9. The method according to claim 7, characterized in that the further attribute indicates a value that is actually available as the in-lane maneuvering space if an obstacle is present in the traffic lane.
 10. A method incorporating the method according to claim 1, for a driver assistance system for the subject vehicle to determine a future trajectory of the subject vehicle based on data provided by the sensor system for detecting the environment, characterized by the following steps: i) surrounding objects and positions thereof are detected using the sensor data, ii) vehicle surroundings including the boundary of the traffic lane of the subject vehicle are represented by the position points having the attributes, and iii) the position points representing the vehicle surroundings are transmitted via a vehicle bus to a control device which determines a future trajectory of the subject vehicle.
 11. A driver assistance system with the sensor system for detecting the environment and a data evaluation unit configured to execute the method according to claim 1, wherein the data evaluation unit is connected via a vehicle bus system to a control device which controls a driver assistance function. 